Sequencers are devices for automatically determining and controlling sequences of events, such as turning on or turning off power supplies. Many Application-Specific Integration Circuits (ASICs), microprocessors and other electronic circuits require multiple power supplies in order to operate. Often, these power supplies must be turned on and off in a specific order to avoid damage to an electronic circuit or to enable an electronic circuit to operate in a proper manner. Also, it may be desirable to initiate turning on one or several power supplies at a particular time slot and wait until these power supplies are on before turning on the next power supply or the next group of power supplies.
Often, the sequencing must involve multiple electronic circuits at different locations on an electronic assembly or at different electronic assemblies. Therefore, to perform sequencing, electrical communications between electronic circuits must be provided. One way to coordinate multiple electronic circuits involved in sequencing is to provide a central or master circuit that has multiple control outputs and status inputs for each sequenced event. Another solution might be to use a serial communication protocol, such as 12C, with an intelligent master controller. However, most communications protocols would not support highly accurate timing of events. Each of these approaches involves significant complexity in the system architecture and/or manufacturing process.
Therefore, there is a need for a new sequencing technique to provide sequencing of events among arbitrary number of electronic circuits using a single wire for transmitting sequencing information.